Low-frequency data are also affected by the earth's ionosphere. The incoming extra-terrestrial wavefronts suffer refraction from the non-uniformity of the ionospheric plasma layers. The presence of plasma gradients across the pierce points to the extragalactic sources results in offsets in source positions, while curvature can change the source flux density [1]}. At the frequencies of interest for CD/EoR science (\(\lesssim \)  150 MHz), the ionospheric effects can become quite significant, affecting data calibration and, subsequently, signal recovery.
